<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    /* 清除默认样式 */
    * {
      margin: 0;
      padding: 0;
    }
    ul,ol {
      list-style: none;
    }
    .lunbo {
      position: relative;
      width: 880px;
      height: 550px;
      border: 1px solid #333;
      margin: 20px auto;
    }
    .lunbo .pic li {
      position: absolute;
      left: 0;
      top: 0;
      width: 880px;
      height: 550px;
      display: none;
    }
    .lunbo .pic .current {
      display: block;
    }
    /* 按钮 */
    .lunbo .btn a {
      position: absolute;
      top: 50%;
      width: 40px;
      height: 40px;
      margin-top: -20px;
      background-color: rgba(255,255,255,0.3);
      font: 20px/40px "宋体";
      text-align: center;
      color: #fff;
      text-decoration: none;
      font-weight: bold;
    }
    .lunbo .btn .leftbtn {
      left: 20px;
    }
    .lunbo .btn .rightbtn {
      right: 20px;
    }
    .lunbo .btn a:hover {
      background-color: rgba(255,255,255,0.6);
    }
    /* 下标 */
    .lunbo .sub {
      position: absolute;
      left: 100px;
      bottom: 50px;
      width: 240px;
    }
    .lunbo .sub li {
      float: left;
      width: 20px;
      height: 20px;
      margin-right: 20px;
      background-color: rgba(255,255,255,0.4);
      font: 12px/20px "微软雅黑";
      text-align: center;
      color: #666;
      cursor: pointer;
    }
    .lunbo .sub .current {
      background-color: #fff;
    }
  </style>
</head>
<body>
    <!-- 13. 给 part1-模块2-任务1 的轮播图静态页面添加JS事件，让其成功滚动 -->
  <!-- 轮播图大结构 -->
  <div class="lunbo" id="lunbo">
    <!-- 图片部分 -->
    <ul class="pic" id="pic">
      <li class="current"><img src="images/lunbo/c1.jpg"></li>
      <li><img src="images/lunbo/c2.jpg"></li>
      <li><img src="images/lunbo/c3.jpg"></li>
      <li><img src="images/lunbo/c4.jpg"></li>
      <li><img src="images/lunbo/c5.jpg"></li>
      <li><img src="images/lunbo/c6.jpg"></li>
    </ul>
    <!-- 按钮 -->
    <div class="btn" >
      <a href="javascript:;" class="leftbtn" id="leftbtn">&lt;</a>
      <a href="javascript:;" class="rightbtn" id="rigthbtn">&gt;</a>
    </div>
    <!-- 小圆点 -->
    <ol class="sub" id="sub">
      <li class="current">1</li>
      <li>2</li>
      <li>3</li>
      <li>4</li>
      <li>5</li>
      <li>6</li>
    </ol>
  </div>
  <script>
      var lunbo = document.getElementById("lunbo");
      var pic = document.getElementById("pic");
      var leftbtn = document.getElementById("leftbtn");
      var rigthbtn = document.getElementById("rigthbtn");
      var sub = document.getElementById("sub");
      var ulLis = pic.children;
      var olLis = sub.children;
      var idx = 0;
      rigthbtn.onclick = function () {
          idx++;
          if (idx > ulLis.length - 1) {
              idx = 0;
          }
          for (var i = 0; i < ulLis.length; i++) {
              ulLis[i].className = "";
              olLis[i].className = "";
          }
          ulLis[idx].className = "current";
          olLis[idx].className = "current";
      }
      leftbtn.onclick = function () {
          idx--;
          if (idx < 0) {
              idx = ulLis.length - 1;
          }
          for (var i = 0; i < ulLis.length; i++) {
              ulLis[i].className = "";
              olLis[i].className = "";
          }
          ulLis[idx].className = "current";
          olLis[idx].className = "current";
      }
      for (var i = 0; i < olLis.length; i++) {
          olLis[i].index = i;
          olLis[i].onclick = function () {
              idx = this.index;
              for (var i = 0; i < ulLis.length; i++) {
              ulLis[i].className = "";
              olLis[i].className = "";
          }
          ulLis[idx].className = "current";
          olLis[idx].className = "current";
          }
      }
  </script>
</body>
</html>